CHICAGO -- At the start of the season, Addison Russell and Kyle Schwarber figured prominently in the Chicago Cubs' future -- but no one thought that future would be this season.

Friday, though, might be remembered as the day both youngsters stepped forward to assume bigger roles as the Cubs began a playoff push.

Before the solid 7-3 victory over the San Francisco Giants at Wrigley Field -- the team's second straight in the crucial four-game set against the World Series champs -- Cubs manager Joe Maddon shuffled his lineup and gave both Russell and Schwarber more responsibility.

Russell shifted over to his natural position of shortstop (pushing Starlin Castro to the bench) and Schwarber was moved to left field to keep his bat in the lineup. Both excelled and were a big part of the Cubs, winners of eight of nine, expanding their lead over the Giants to 1 1/2 games in the race for the second wild-card playoff spot in the National League.

Russell, 21, was rushed to the major leagues in April when the Cubs needed a second baseman even though he played only a handful of games at the position in the minors. He's done well at second, but the consensus in the Cubs clubhouse is that he looks like a natural at short.

"Addison had a wonderful day at shortstop," Maddon said. "Two things: the tag play on the stolen base and then the play from [Jon Lester] on the double play. That's so athletic."

In the second inning, San Francisco shortstop Brandon Crawford attempted to steal second base. Catcher David Ross' throw was wide to the second-base position side of the bag, but Russell made a diving catch on the throw and tagged out Crawford in the same motion.

In the seventh, with the Giants attempting to rally, Crawford hit a comebacker with runners on first and second and none out. Lester fielded the ball cleanly, but his throw to second base was low and wide to the shortstop side. Russell fell down catching the throw, but somehow touched the bag and got up to throw Crawford out at first base.

The Giants challenged, contending that Russell didn't touch the second-base bag, but the call was upheld on review.

"Having him at second base, you don't really get to see his athleticism," Lester said of Russell. "It's a little bit, I guess, easier position. But today, it was unbelievable the stuff he was able to do out there. That's huge when you can give [Castro] a day off and have that replace him. That’s big for us."

Lester might not been aware that Castro wasn't given a day off. Maddon made it clear Russell will play short again on Saturday.

Schwarber, who began the season at Double-A Tennessee, will be in the lineup as well because he continued his torrid hitting by going 2-for-5 with two runs scored and two runs batted in. More impressively, the player still learning how to play catcher looked smooth in the outfield.

"He runs or moves better than he looks," Maddon said. "I don't mean to criticize his appearance. I'm just saying he doesn’t have that speedster look about him, but he moves well, runs well. On a ground ball, watch him run to first base, he moves. First to third, second to home and routes in the outfield."

Schwarber made a nice running catch in the left-center gap on a fly ball by Hunter Pence in the second inning and then went back well on a drive by Angel Pagan in the third inning, hauling in the ball just before reaching the wall.

Like he does with most things, Schwarber downplayed his play in left.

"I've played the position before, last year and in college," he said. "I feel comfortable out there. People see a big guy like me and think, 'He doesn't belong out there.' I think I can hold my own."

Lester, not one to heap over-the-top praise on anyone, paid Schwarber the ultimate compliment when asked if he was surprised by how well the rookie is performing.

"Now that I've got to know him, no," Lester said. "He's a baseball player. I mean, there are not many guys like that that can ... I don't know how many games he's played in left field, but he made some plays today that looked like he had been an everyday left fielder.

"He's a baseball player. He understands the game, he understands the situation. He doesn't let the situation get too much of him. He goes out there and plays the game, whether he's catching or whether he's playing left field. If you stuck him at first base, I'm sure he would do the same thing. It's been impressive to see and it's been impressive to see the adjustments he's made offensively and defensively behind the plate."